A differentiator has a transfer function whose

magnitude decreases linearly with frequency

phase increases linearly with frequency

magnitude increases linearly with frequency

magnitude decreases linearly with frequency

Identify the correct definition for phase Margin and Gain margin:

I. Gain margin is a factor by which the system gain can be decreased to drive the system to the verse of instability.II. Phase margin is the additional phase lead at the gain cross over frequency to bring the system to verge of instability.

I. Gain margin is a factor by which the system gain can be increased to drive the system to the verse of instability.II. Phase margin is the additional phase lead at the gain cross over frequency to bring the system to verge of instability.

I. Gain margin is a factor by which the system gain can be increased to drive the system to the verse of instability.II. Phase margin is the additional phase lag at the gain cross over frequency to bring the system to verge of instability.

I. Gain margin is a factor by which the system gain can be decreased to drive the system to the verse of instability.II. Phase margin is the additional phase lead at the gain cross over frequency to bring the system to verge of instability.

I. Gain margin is a factor by which the system gain can be decreased to drive the system to the verse of instability.II. Phase margin is the additional phase lag at the gain cross over frequency to bring the system to verge of instability.

Directions: It consists of two statements, one labelled as the ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answers to these items using the codes given below:Statement (I):A large resonance peak in frequency response also corresponds to a large peak overshoot in transient response.Statement (II):All the systems which exhibit overshoot in time response will also exhibit resonance peak in frequency response.

Statement (I) is false but Statement (II) is true

Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I)

Statement (I) is true but Statement (II) is false

Statement (I) is false but Statement (II) is true

From the Nichols chart, one can determine the following quantities pertaining to a closed-loop system:

Magnitude, bandwidth, and phase

A closed-loop control system is stable if the Nyquist plot of the corresponding open-loop transfer function

Encircles the s-plane point (0 − j1) in the clockwise direction as many times as the number of right-half s-plane poles.

Encircles the s-plane point (−1 + j0) in the counterclockwise direction as many times as the number of right-half s-plane poles.

Encircles the s-plane point (0 − j1) in the clockwise direction as many times as the number of right-half s-plane poles.

Encircles the s-plane point (−1 + j0) in the counterclockwise direction as many times as the number of left-half s-plane poles.

Encircles the s-plane point (−1 + j0) in the counterclockwise direction as many times as the number of right-half s-plane zeros.

Assertion: Gain margin is the factor by which the system gain can be decreased to drive it to the verge of instability.Reason: Gain margin is the reciprocal of the gain at a frequency at which the phase angle becomes 180°

Both A and R are true and R is the correct explanation of A

Both A and R are true and R is not the correct explanation of A

An open loop system represented by the transfer function $G\left( s \right) = \frac{{\left( {s - 1} \right)}}{{\left( {s + 2} \right)\left( {s + 3} \right)}}$ is

Unstable and the minimum phase type

Stable and of the minimum phase type

Stable and of the non-minimum phase type

Unstable and the minimum phase type

Unstable and of the non-minimum phase type

Direction: The following item consists of two statements, one labeled as ‘Statement (I) and the other as ‘Statement (II). You are to examine these two statements carefully and select the answers to these items using the code given below:Statement (I): For an unstable feedback system, the gain margin is negative or the phase margin is positive.Statement (II): For a stable feedback system, both gain margin and phase margin must be positive.

Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

Both Statement (I) and Statement (II) are individually true but Statement (II) is NOT the correct explanation of Statement (I)

Statement (I) is true but Statement (II) is false

Statement (I) is false but Statement (II) is true

A bode magnitude plot for the transfer function G(s) of a plant is shown in the figure. Which one of the following transfer functions best describes the plant?

$\frac{{100\left( {s + 10} \right)}}{{s + 1000}}$

$\frac{{10\left( {s + 10} \right)}}{{s\left( {s + 10} \right)}}$

$\frac{{s + 1000}}{{10s\left( {s + 10} \right)}}$

$\frac{{s + 1000}}{{10\left( {s + 10} \right)}}$

Each of the items consists of two statements, one labeled as ‘Statement (I)’ and the other as ‘Statement (II)’. Examine these two statements carefully and select the answers to these items:Statement (I): Elements with non-minimum phase transfer functions introduce large phase lags with increasing frequency resulting in complex compensation problems.Statement (II): Transportations lag commonly encountered in process control systems is a non-minimum phase element.

Both Statement (I) and Statement(II) are individually true but Statement (II) is not the correct explanation of Statement(I)

Both Statement (I) and Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I)

Both Statement (I) and Statement(II) are individually true but Statement (II) is not the correct explanation of Statement(I)

Statement (I) is true but Statement (II) us false

Statement (I) is false but Statement (II) is true

Nichols’ chart is used to determine

settling time due to step input

A minimum phase transfer function has

Poles in the left half of the s-plane

Zeros in the left half of the s-plane

Poles in the left half of the s-plane and zeros in the right half of the s-plane

No poles and zeros in the right half of the s-plane or on the jω axis excluding origin

Consider the feedback system shown in the figure. The Nyquist plot of G(s) is also shown. Which one of the following conclusions is correct?

G(s) is a strictly proper transfers function

G(s) is a stable and minimum phase transfer function.

The closed-loop system is unstable for sufficiently large & positive K.

If the s-plane counter enclose 3 zeros and 2 poles contour will encircle the origin of q(s) plane

Once in counter clockwise direction

Twice in counter clockwise direction

93 + Mcqs in Frequency Response in Electronic Devices Circuits Page 2 McqOptions

51.	A differentiator has a transfer function whose
A.	phase increases linearly with frequency
B.	magnitude remains constant
C.	magnitude increases linearly with frequency
D.	magnitude decreases linearly with frequency
Answer» D. magnitude decreases linearly with frequency

52.	A stable real linear time-invariant system with single pole at p, has a transfer function \(H\left( s \right) = \frac{{{s^2} + 100}}{{s - p}}\) with a dc gain of 5. The smallest positive frequency, in rad/s at unity gain is closest to:
A.	8.84
B.	11.08
C.	78.13
D.	122.87
Answer» B. 11.08

53.	A unity feedback system has the open loop transfer function \(G(s) = \frac {2s}{(s+1)(s+2)}\). The steady state response of the closed loop system to a unit step reference input is
A.	unit step
B.	unit ramp
C.	unit impulse
D.	zero
Answer» E.

54.	For an LTI system, the Bode plot for its gain is as illustrated in the figure shown. The number of system poles Np and the number of system zeros Nz in the frequency range 1 Hz ≤ f ≤ 107 Hz is
A.	Np = 5, Nz = 2
B.	Np = 6, Nz = 3
C.	Np = 7, Nz = 4
D.	Np = 4, Nz = 2
Answer» C. Np = 7, Nz = 4

55.	Consider the system\(G\left( s \right)H\left( s \right) = \frac{1}{{s\left( {1 + 3s} \right)\left( {1 + 5s} \right)}}\)Select the appropriate phase crossover frequency from the following options.
A.	6 rad/sec
B.	2.46 rad/sec
C.	3.23 rad/sec
D.	0.2582 rad/sec
Answer» E.

56.	Consider the following statements regarding 'relative stability'Relative stability can be determined1. in terms of gain margin only2. in terms of phase margin only3. in terms of gain margin and phase margin and location of poles in s-plane4. in relation to another identified system
A.	1 and 2
B.	2 and 3
C.	3 and 4
D.	1 and 4
Answer» D. 1 and 4

57.	For a type 1 system, the low frequency asymptote of its Bode plot will have a slope of
A.	0 dB/decade
B.	6 dB/decade
C.	20 dB/decade
D.	-20 dB/decade
Answer» E.

58.	Consider a stable system with the transfer function \(\left( s \right) = \frac{{{s^p} + {b_1}{s^{p - 1}} + \ldots + {b_p}}}{{{s^q} + {a_1}{s^{q - 1}} + \ldots + {a_q}}}\)Where b1, …, bp and a1, …, aq are real-valued constants. The slope of the Bode log magnitude curve of G(s) converges to – 60 dB/decade as ω → ∞. A possible pair of values for p and q is
A.	p = 0 and q = 3
B.	p = 1 and q = 7
C.	p = 2 and q = 3
D.	p = 3 and q = 5
Answer» B. p = 1 and q = 7

60.	Bode magnitude plot of a system is 0 dB and its maximum phase is -180 degree. Possible transfer function of the system is
A.	\(\frac{{s - 1}}{{1 + s}}\)
B.	\(\frac{1}{{{s^2}}}\)
C.	\({e^{ - s\tau }}\)
D.	None of these
Answer» B. \(\frac{1}{{{s^2}}}\)

62.	For a Phase Locked Loop system, the open-loop transfer function is\(G(s) = \frac {1000}{s\left(\frac {s}{1192} + 1\right)}\)The phase margin is 50° and the crossover frequency is approximately 1000 rad / s. A time delay is introduced in the phase detector reducing the phase margin to 40°. The maximum permissible time delay (in seconds) is:
A.	10-4
B.	0.174
C.	1.192 × 10-3
D.	0.174 × 10-3
Answer» E.

63.	From the Nichols chart, one can determine the following quantities pertaining to a closed-loop system:
A.	Magnitude, bandwidth, and phase
B.	Bandwidth and phase only
C.	Magnitude and phase only
D.	Bandwidth only
Answer» B. Bandwidth and phase only

65.	In a third order LPF the output rolls at rate of _______.
A.	-3 dB per decade
B.	-9 dB per decade
C.	-20 dB per decade
D.	-18 dB per octave
Answer» E.

76.	If the constant 'k' is negative, then what would be its contribution to the phase plot:
A.	90 degrees
B.	45 degrees
C.	180 degrees
D.	0 degree
Answer» E.

80.	Consider the transfer function (0.1 + 0.01s) for a PD controller. What is the frequency at which the magnitude is 20 dB (by using asymptotic Bode’s plot)?
A.	2000 r/s
B.	1000 r/s
C.	200 r/s
D.	100 r/s
Answer» C. 200 r/s

85.	A_SERIES_RESONANT_CIRCUIT_HAS_L_=_1_MH_AND_C_=_10_F._THE_REQUIRED_R_(IN_OHM)_FOR_THE_BW_=_15_9_._HZ_IS?$
A.	0.1
B.	0.2
C.	0.0159
D.	500
Answer» C. 0.0159

68.	Consider the Nyquist plot of the second-order underdamped system shown in the below figureThe resonant frequency corresponding to the Nyquist plot is
A.	ω1
B.	ω2
C.	ω3
D.	ω4
Answer» C. ω3

69.	From the below given Nyquist plot, calculate the number of open-loop poles on the right-hand side of the s-plane for the closed-loop system to be stable.
A.	1
B.	2
C.	0
D.	-1
Answer» B. 2

71.	A bode magnitude plot for the transfer function G(s) of a plant is shown in the figure. Which one of the following transfer functions best describes the plant?
A.	\(\frac{{100\left( {s + 10} \right)}}{{s + 1000}}\)
B.	\(\frac{{10\left( {s + 10} \right)}}{{s\left( {s + 10} \right)}}\)
C.	\(\frac{{s + 1000}}{{10s\left( {s + 10} \right)}}\)
D.	\(\frac{{s + 1000}}{{10\left( {s + 10} \right)}}\)
Answer» E.

73.	Gain margin is the factor by which the system gain can be increased to drive it to
A.	stability
B.	oscillation
C.	the verge of instability
D.	critically damped state
Answer» D. critically damped state

74.	Nichols’ chart is used to determine
A.	transient response
B.	closed-loop frequency response
C.	open-loop frequency response
D.	settling time due to step input
Answer» C. open-loop frequency response

75.	An FIR system is described by the system function\(H\left( s \right) = 1 + \frac{7}{2}{z^{ - 1}} + \frac{3}{2}{z^{ - 2}}\;\;\;\) The system is
A.	maximum phase
B.	minimum phase
C.	mixed-phase
D.	zero phase
Answer» D. zero phase

78.	Consider the feedback system shown in the figure. The Nyquist plot of G(s) is also shown. Which one of the following conclusions is correct?
A.	G(s) is an all-pass filter
B.	G(s) is a strictly proper transfers function
C.	G(s) is a stable and minimum phase transfer function.
D.	The closed-loop system is unstable for sufficiently large & positive K.
Answer» E.

79.	Consider the following statements with reference to the response of a control system:1. A large resonant peak corresponds to a small overshoot in transient response.2. A large bandwidth corresponds to slow response.3. The cut-off rate indicates the ability of the system to distinguish the signal from noise4. Resonant frequency is indicative of the speed of transient response.Which of the above statements are correct?
A.	1 and 2
B.	2 and 3
C.	1 and 4
D.	3 and 4
Answer» E.

81.	If the s-plane counter enclose 3 zeros and 2 poles contour will encircle the origin of q(s) plane
A.	Once in clockwise direction
B.	Once in counter clockwise direction
C.	Thrice in clockwise direction
D.	Twice in counter clockwise direction
Answer» B. Once in counter clockwise direction

82.	For the Nichols plot shown, the system is:
A.	Unstable
B.	Stable
C.	Overdamped
D.	Critically stable
Answer» C. Overdamped

Explore topic-wise MCQs in Electronic Devices Circuits.

A differentiator has a transfer function whose

A stable real linear time-invariant system with single pole at p, has a transfer function \(H\left( s \right) = \frac{{{s^2} + 100}}{{s - p}}\) with a dc gain of 5. The smallest positive frequency, in rad/s at unity gain is closest to:

A unity feedback system has the open loop transfer function \(G(s) = \frac {2s}{(s+1)(s+2)}\). The steady state response of the closed loop system to a unit step reference input is

For an LTI system, the Bode plot for its gain is as illustrated in the figure shown. The number of system poles Np and the number of system zeros Nz in the frequency range 1 Hz ≤ f ≤ 107 Hz is

Consider the system\(G\left( s \right)H\left( s \right) = \frac{1}{{s\left( {1 + 3s} \right)\left( {1 + 5s} \right)}}\)Select the appropriate phase crossover frequency from the following options.

Consider the following statements regarding 'relative stability'Relative stability can be determined1. in terms of gain margin only2. in terms of phase margin only3. in terms of gain margin and phase margin and location of poles in s-plane4. in relation to another identified system

For a type 1 system, the low frequency asymptote of its Bode plot will have a slope of

Identify the correct definition for phase Margin and Gain margin:

Bode magnitude plot of a system is 0 dB and its maximum phase is -180 degree. Possible transfer function of the system is

From the Nichols chart, one can determine the following quantities pertaining to a closed-loop system:

A closed-loop control system is stable if the Nyquist plot of the corresponding open-loop transfer function

In a third order LPF the output rolls at rate of _______.

Assertion: Gain margin is the factor by which the system gain can be decreased to drive it to the verge of instability.Reason: Gain margin is the reciprocal of the gain at a frequency at which the phase angle becomes 180°

An open loop system represented by the transfer function \(G\left( s \right) = \frac{{\left( {s - 1} \right)}}{{\left( {s + 2} \right)\left( {s + 3} \right)}}\) is

Consider the Nyquist plot of the second-order underdamped system shown in the below figureThe resonant frequency corresponding to the Nyquist plot is

From the below given Nyquist plot, calculate the number of open-loop poles on the right-hand side of the s-plane for the closed-loop system to be stable.

A bode magnitude plot for the transfer function G(s) of a plant is shown in the figure. Which one of the following transfer functions best describes the plant?

Gain margin is the factor by which the system gain can be increased to drive it to

Nichols’ chart is used to determine

An FIR system is described by the system function\(H\left( s \right) = 1 + \frac{7}{2}{z^{ - 1}} + \frac{3}{2}{z^{ - 2}}\;\;\;\) The system is

If the constant 'k' is negative, then what would be its contribution to the phase plot:

A minimum phase transfer function has

Consider the feedback system shown in the figure. The Nyquist plot of G(s) is also shown. Which one of the following conclusions is correct?

Consider the transfer function (0.1 + 0.01s) for a PD controller. What is the frequency at which the magnitude is 20 dB (by using asymptotic Bode’s plot)?

If the s-plane counter enclose 3 zeros and 2 poles contour will encircle the origin of q(s) plane

For the Nichols plot shown, the system is:

In the Bode plot of a unity feedback control system, the value of phase of G(jω) at the gain cross over frequency is -125°. The phase margin of the system is

For a unity feedback control system, if its open-loop transfer function is given by \(\frac{10}{(s+5)^3}\), then its gain margin will be

A_SERIES_RESONANT_CIRCUIT_HAS_L_=_1_MH_AND_C_=_10_F._THE_REQUIRED_R_(IN_OHM)_FOR_THE_BW_=_15_9_._HZ_IS?$

For_the_RLC_parallel_resonant_circuit_when_R_=_8k,_L_=_40_mH_and_C_=_0.25_F,_the_quality_factor$

A parallel circuit has R = 1k ohm , C = 50 ¬¨¬®¬¨¬µF and L = 10mH. The quality factor at resonance i?#

A parallel RLC circuit has R 1 k and C 1 F. The quality factor at resonance is 200. The value of inductor is

The value of C is

The value of R (in ohm) is

The quality factor is

The value of inductor is

1-Q.3) A parallel resonant circuit has a resistance of 2k ohm and half power frequencies of 86 kHz and 90 kHz.

83.	In the Bode plot of a unity feedback control system, the value of phase of G(jω) at the gain cross over frequency is -125°. The phase margin of the system is
A.	-125°
B.	– 55°
C.	55°
D.	125°
Answer» D. 125°

84.	For a unity feedback control system, if its open-loop transfer function is given by \(\frac{10}{(s+5)^3}\), then its gain margin will be
A.	20 dB
B.	40 dB
C.	60 dB
D.	80 dB
Answer» C. 60 dB

86.	For_the_RLC_parallel_resonant_circuit_when_R_=_8k,_L_=_40_mH_and_C_=_0.25_F,_the_quality_factor$
A.
B.	40
C.	20
Answer» C. 20

87.	A parallel circuit has R = 1k ohm , C = 50 ¬¨¬®¬¨¬µF and L = 10mH. The quality factor at resonance i?#
A.	100
B.	90.86
C.	70.7
D.	None of the above
Answer» B. 90.86

88.	A parallel RLC circuit has R 1 k and C 1 F. The quality factor at resonance is 200. The value of inductor is
A.	35.4 H
B.	25 H
C.	17.7 H
D.	50 H
Answer» D. 50 H

89.	The value of C is
A.	2 ¬¨¬®¬¨¬µF
B.	28.1 ¬¨¬®¬¨¬µF
C.	10 ¬¨¬®¬¨¬µF
D.	14.14 ¬¨¬®¬¨¬µF
Answer» C. 10 ¬¨¬®¬¨¬µF

90.	The value of R (in ohm) is
A.	40
B.	56.57
C.	80
D.	28.28
Answer» D. 28.28

92.	The value of inductor is
A.	4.3 mH
B.	43 mH
C.	0.16 mH
D.	1.6 mH
Answer» D. 1.6 mH

93.	1-Q.3) A parallel resonant circuit has a resistance of 2k ohm and half power frequencies of 86 kHz and 90 kHz.
A.
B.	6 ¬¨¬®¬¨¬µF
C.	20 nF
Answer» C. 20 nF